Method for the flame-retardant processing of textile materials

ABSTRACT

A process is proposed for the fireproofing treatment of textile materials by impregnating them initially with a melamine-formaldehyde resin or organosilicon substances, and then with a solution of a complex compound of the ammonia salt of amidoalkylphosphonic acid with ammonium chloride. Materials treated in accordance with the invention have reduced combustibility and low toxicity of the gases given off during combustion.

FIELD OF TECHNOLOGY

The invention relates to a technology for producing polymer materials,including textiles, with reduced combustibility, low toxicity of thegases given off during combustion and low smoke-forming capability.

Chemical fibres and textile materials are used in various industries,including for making composition materials used in road transport and inaircraft and ship building. Woven and knitted fabrics are used asdecorative finishing materials in places where people are present inlarge numbers (theatres, clubs, hospitals, museums and hotels), in thebuilding industry and in transport.

Textile materials are widely used in everyday life and for makingspecial clothing for workers in practically every industry.

At the same time, the easy flammability and combustibility of mostindustrially produced chemical fibres and textile materials constitute asignificant problem. They have a low spontaneous combustion temperatureand a high burning rate.

PRIOR ART

A method of fire protection impregnation based on the use oforthophosphoric acid and compounds containing nitrogen (dicyanodiamide,carbamide, melamine, guanidine etc.) is widely used on an industrialscale in Russia. In this method, the fabric is treated with acomposition including phosphoric acid and one of the listed

nitrogen-containing compounds and is subjected to heat treatment (Ye. A.Blekhman, The Manufacture of Incombustible Cotton Fabrics, Moscow,1950-189 pp.). This process has considerable faults, namely a markedreduction in the resistance of the fabric to tearing load (a reductionin tearing strength of 40-50%) and low efficiency of the fire resistanceeffect for fabrics composed of a mixture of synthetic and cellulosefibres.

There is a known fire protection composition (GB application 2273720)for the treatment of fabrics, non-woven materials and carpet products,consisting of an aqueous solution of inorganic salts (ammoniumphosphate, ammonium sulphate, ammonium bromide and mixtures of these inquantity 12-20% of the composition) and mineral acid (sulfuricacid-—0.4-0.6 wt. % of the composition), which assists the solution inpenetrating into the fibres of the material and which raises thestability of the bonding of the combustion retarder with the fibres ofthe textile material. A fault of this composition is the low efficiencyof the fire protection effect for materials containing synthetic fibres.

The compositions FR Cros 282, 330 and 334, based on ammoniumpolyphosphates (Catalogue of Combustion Retarders, Bolid GmbH,Frankfurt, 1996), are used for the fire protection of textiles. Thecomposition FR Cros 282 includes modified mono ammonium phosphate with10% ammonium polyphosphate in combination with melamine andpentaerythritol in the ratio 3:1:1. The concentration of thiscomposition in the aqueous suspension used for the treatment of textilesis 500 g/liter.

The composition FR Cros 330 is an aqueous vinyl acetate suspension withammonium polyphosphate, in which the content of the solid matter is 50%.The composition FR Cros 334 includes modified ammonium pyrophosphate. Itis used for the fire protection of wood, paper and textiles. For allthese compositions, the fire protection effect is achieved with theintroduction of combustion retarders into the material in quantity30-40%, which leads to a reduction in the physico-mechanical indicatorsand feel properties of the fabrics.

There is a known fire protection process for cellulose materials, basedon the use of tetra-(hydroxymethyl)-phosphonium chloride (THPC) andpolyfunctional compounds containing nitrogen, which has been given thename “Proban” (U.S. Pat. No. 2,912,466). To make cellulose materialsfire-resistant by this process, a polycondensation process is firstcarried out between THPC and carbamide at a molar ratio of thecomponents of 1:1. The cellulose material is impregnated with an aqueoussolution of the precondensate and dried.

The formation of a polymer insoluble in water and organic solvents isachieved by treating the material with ammonia solution or gaseousammonia at 140-160° C. This treatment is called “Probanfinish-210”. Theproblems with this method include a reduction in the strength of thefabric by 30% and an increase in the stiffness of the material. Thereare also data indicating high toxicity of the combustion products fromcellulose materials containing THPC. When thermolysis of thefire-protected cellulose takes place in the 200-300° C. range, theemission of phosphatin is observed (Spect. Chem., 1984, V. 4, pp.17-20).

The most effective treatment for cellulose fabrics and for fabrics madeof a mixture of cellulose and synthetic fibres is one called“Pyrovatex-CP” (Technico-economic Information Bulletin on LightIndustry, 1975, No. 9, pp. 75-76). The fabric is impregnated with anaqueous solution containingN-hydroxymethyldi-(methoxy)-phosphonopropionamide, carbamide, across-linking agent and a catalyst. It is then dried, heat-stabilised ata temperature of 140-160° C. and washed. When cotton fabrics are treatedby the “Pyrovatex-CP” method, the fire-resistant properties are achievedat a content of 2.0% of phosphorus in the material.

The toxicity of the pyrolysis products of the materials is a significantproblem for fabrics protected against fire by the use ofN-hydroxymethyldi-(methoxy)-phosphono-propionamide. It has been shown(Textilveredelung, 1970, V. 6, pp. 486-497) that at a temperature of300-400° C., considerable quantities of methanol are emitted. Therelationship revealed rules out the use of fabrics fire-protected inthis way for making special clothing for workers and also for thefireproofing of materials used in enclosed spaces.

A study of the comparative effectiveness of the phosphorus-containingpreparations “Proban” and “Pyrovatex-CP” has shown that theireffectiveness is different for cotton fabrics and fabrics made of amixture of cotton and polyester fibres.

In all the studied variants of the treatment of fabrics made of amixture of fibres by the “Pyrovatex-CP” method, the materials had higherfire protection indicators. However, in both cases, fire-protectedfabrics can only be produced if they contain not more than 10% ofsynthetic fibre (Text. Res. J., V. 45, No. 8, p. 586).

The main problem with the known “Proban” and “Pyrovatex-CP” processes istheir low effectiveness for materials made of a mixture of cellulose andsynthetic fibres and pure synthetic fibres.

UK Patent 2205868 for the fire protection treatment of fabrics based oncellulose with other fibres proposes carrying out the “Proban” methodtreatment at least twice, and also oxidising the phosphorus into thepentavalent form by treating the fabric dried out after the first orsecond treatment with a solution of hydrogen peroxide.

U.S. Pat. No. 4,732,789 proposes a two-stage process of treating fabricsmade of a mixture of cotton with polyester or nylon. The fabric isinitially treated by the “Proban” method, after whichhexabromocyclododecane or cyclic phosphonates are used to provide fireprotection for the polyester or nylon components. The treated fabric isvulcanised, and if hexabromocyclododecane is used, it is heated to above182° C. to melt the fireproofing compound. The two-stage nature of theprocess and the requirement for vulcanisation at high temperatures makesit very difficult for this invention to be applied in practice.

A preparation called “Pyrofix”, based on dialkyl phosphonamide ofcarbonic acid (Catalogue of Chemical Products, JSC “Ivkhimprom”, 1995,pp. 22-23), has been proposed for imparting fire protection propertiesto textile materials containing cellulose.

To impart fire protection properties, it is recommended that theimpregnating solution should contain the following (g/liter):

pyrofix 350-400, metazine 6Y 60-80, polyethylene emulsion 20-30,orthophosphoric acid 10.

The problem with this preparation is the low efficiency of thefireproofing effect for fabrics made of a mixture of cellulose andsynthetic fibres.

USSR Authorship Certificate No. 1427017 describes a fire protectiontreatment for textile materials using a composition including methylphosphonic acid diamide, ammonium chloride, carbamide, glycazine ordimethyl polyethylene carbamide and sulfocide-31. The use of thiscomposition makes it possible to obtain fire-protected textile materialsmade from a mixture of cellulose and synthetic fibres. The problems withthis method are: the low hydrolytic stability of the methyl phosphonicacid diamide, and the instability of aqueous solutions containing bothmethyl phosphonic acid diamide and glycazine (the formation of aoligomer product insoluble in water, which has a low reaction capabilityrelative to the functional groups of polymer materials). Fire-protectedtextile materials can only be obtained if there is a high content ofcombustion retarder on the fabric (up to 30% of the weight of thematerial).

Substance of the Invention Explained

Although there are known and widely used compositions of various kindsserving to reduce the combustibility of textile materials of natural(cotton, flax, wool) and chemical (viscose, cupro-ammonium, polyester,polycaproamide) fibres and mixtures of them in various compositions, theproblem of creating new and more effective processes for the fireprotection of materials and fire-protective compositions remains urgent.This invention is primarily aimed at solving this problem.

Other aims of the invention are:

to reduce the smoke-forming capability of fire-protected textilematerials subjected to pyrolysis and combustion;

to increase the resistance of the fireproofing properties of thematerial to wet treatments and chemical cleaning;

to impart a range of fire-protection and water-and-oil-repellentproperties to textile materials;

to enable these things to be done using simple and reliable equipmentexisting in the finishing production lines of textile factories.

The invention described below solves these problems.

The first aspect of this invention is the creation of a process for thefire protection treatment of textile materials which includes thefollowing sequence of operations:

impregnation of the material with an aqueous solution of a melamine-type(melamine-formaldehyde) resin;

the drying of the material;

impregnation of the material with an aqueous solution containingcarbamide and a complex compound of the ammonium salt ofamidoalkylphosphonic acid with ammonium chloride, Formula

where R is an alkyl radical with 1-3 carbon atoms;

the drying of the material and its heat treatment at a temperature of140-170 C.

In addition to the operations listed above, the material may also bewashed and dried after heat treatment.

Compounds containing silicon may be used instead of melamine-type resinfor impregnating the material at the first stage of the fire protectionprocess. Furthermore, these substances (melamine-type resin andsilicon-containing compounds) may be used together.

Silicon-containing compounds, like melamine-type resin, are used in thetextile industry as auxiliary substances at the final stage of finishingtextile materials of various compositions. The presence of functionallyactive groups in the melamine-type resins and silicon-containingcompounds makes it possible for them to interact both with thefunctional groups of the phosphorus-containing combustion retarder andwith the functional groups of the macromolecules of the polymers inpolycondensation reactions. The course of these reactions leads to ahigher degree of fixation of the combustion retarder on the fabric andto greater resistance of the fireproofing effect to wet treatments andchemical cleaning. The combined use of melamine-type resins andsilicon-containing compounds improves the feel of the fabric and itsresistance to wear.

Another aspect of the invention is the creation of a composition for thefire-protection treatment of textile materials, which consists of anaqueous solution of carbamide and a complex compound of the ammoniumsalt of amidoalkylphosphonic acid with ammonium chloride as in Formula(I).

The advisable concentration of these components per liter of aqueoussolution comprises:

complex compound, Formula (I) 200-350 g/liter; carbamide 20-40 g/liter.

To reduce the smoke-forming capability of the protected materials, it isadvisable to add anion complexes of metals, in particular W, Zr and Ti,in a concentration of 2-10 g/liter.

To impart a range of fire-protection and water and oil repulsionproperties to the materials, it is advisable to introduce latexescontaining fluorine into the fireproofing composition in a concentrationof 30-50 g/liter.

Furthermore, organosilicon substances may be introduced into thefireproofing composition as a water repellent.

The patent protection also extends to textile materials of naturalfibres (cotton, flax, wool), of chemical fibres (in particular viscose,cupro-ammonium, polyester and polycaproamide) and mixtures of them ofvarious compositions, if they are subjected to fireproofing treatment inaccordance with this invention.

The invention is further illustrated by examples of its implementation.

EXAMPLE NO. 1

A cotton fabric is impregnated with an aqueous solution of metazine 20g/liter, dried, impregnated with an aqueous solution of a complexcompound of the ammonium salt of amidoalkylphosphonic acid with ammoniumchloride (AAPC for short) 300 g/liter and carbamide 30 g/liter, dried,heat treated at 150° C. for five min., washed with water and dried. Themodified fabric had an AI of 32.5%, no residual combustion time.(AI=Acid Index, i.e. the minimum content of acid in a mixture withnitrogen, for which stable combustion of the specimen takes place: GOST12.1.044-89).

EXAMPLE NO. 2

A fabric composed of a mixture of cotton yam and polyester fibre (fibreratio 67:33%) is impregnated with an aqueous solution of glycazine 30g/liter, dried, impregnated with an aqueous solution of AAPC 300 g/literand carbamide 40 g/liter, dried, heat-treated at 160° C. for five min.,washed with water and dried. AI=31.9%, no residual combustion time.

EXAMPLE NO. 3

A fabric composed of a mixture of cotton yarn and polyester fibre (fibreratio 67:33%) is treated in accordance with Example No. 2, but for thesecond impregnation (aqueous solution of AAPC and carbamide), awater-repellent liquid containing silicon (GKZh-10) is also introducedin quantity 30 g/liter. AI=32.3%.

EXAMPLE NO. 4

A fabric composed of a mixture of viscose and polyester fibres (fibreration 50:50%) is impregnated with an aqueous solution of glycazine 30g/liter, dried, impregnated with an aqueous solution of AAPC 350 g/literand carbamide 40 g/liter, dried, heat-treated at 165° C. for five min.,washed with water and dried. AI=30.1%.

EXAMPLE NO. 5

A fabric composed of a mixture of viscose and polyester fibres (fibreratio 50:50%) is treated in accordance with example No. 4, but duringthe second impregnation, the water repellent aminopropyl triethoxysilane(mark AGM-9) is also added in quantity 50 g/liter. AI=32.0%.

EXAMPLE NO. 6

A fabric composed of a mixture of viscose fibre (20%), cotton (51%) andnitron (29%) is treated with an aqueous solution of glycazine 30g/liter, dried, impregnated with an aqueous solution of AAPC 350 g/literand carbamide 40 g/liter, dried, heat-treated at 160° C. for seven min.,washed with water and dried. AI=33%.

EXAMPLE NO. 7

A fabric composed of a mixture of cotton (62%), polycaproamide (18%) andacetate (20%) is treated in accordance with Example No. 6. AI=30.6%.

EXAMPLE NO. 8

A fabric composed of a mixture of wool (54% and cotton (46%) is treatedwith an aqueous solution of glycazine 30 g/liter, dried, impregnatedwith a solution of AAPC 250 g/liter and carbamide 40 g/liter with theaddition of potassium hexafluorotitanate 10 g/liter, dried, heat-treatedat 165° C. for five min., washed with water and dried. AI=36.2%.

EXAMPLE NO. 9

A fabric composed of a mixture of cupro-ammonium fibre (59%), wool (36%)and caprone (5%) is treated in accordance with Example No. 8. AI=32.8%.

EXAMPLE NO. 10

A fabric composed of a mixture of cotton (57%), flax (29%) and polyesterfibre (14%) is treated in accordance with example No. 5. AI=34.5%.

EXAMPLE NO. 11

A polyester fabric is impregnated with an aqueous solution of glycazine20 g/liter and aminopropyl triethoxysilane 40 g/liter, dried,impregnated with an aqueous solution of AAPC 350 g/liter and carbamide40 g/liter, dried, heat-fixed at 170° C. for 10 min., washed and dried.AI=29.1%.

EXAMPLE NO. 12

A polyester fabric is impregnated with an aqueous solution ofaminopropyl triethoxysilane 50 g/liter, dried, impregnated with anaqueous solution of AAPC 350 g/liter and carbamide 35 g/liter, dried,heat-treated at 170° C. for 10 min., washed and dried. AI=28.0%.

EXAMPLE NO. 13

A polyester fabric is impregnated with an aqueous solution of glycazine20 g/liter, dried, impregnated with an aqueous solution of AAPC 350g/liter, carbamide 30 g/liter and water-repellent organosilicon liquid(GKZh-10) 40 g/liter, dried, heat-treated at 165° C. for 10 min., washedand dried. AI=30.0%.

EXAMPLE NO. 14

A cotton fabric is impregnated with an aqueous solution of metazine 20g/liter, dried, impregnated with an aqueous solution of AAPC 300g/liter, carbamide 30 g/liter and perfluoroheptylacrylate 40 g/liter,dried, heat-treated at 150° C. for five min., washed with water anddried. The modified fabric had AI 33.7% and water resistance 160 mm ofwater column.

EXAMPLE NO. 15

A fabric composed of a mixture of cotton yarn and polyester fibre (ratio67:33%) is treated in accordance with example No. 2, butperfluoroheptylacrylate is also introduced into the AAPC and carbamidesolution in quantity 30 g/liter. AI=33.4%, water resistance 190 mm ofwater column.

EXAMPLE NO. 16

A fabric composed of a mixture of cotton yarn and polyester fibre (ratio50:50%) is impregnated with an aqueous solution of glycazine 20 g/liter,dried, impregnated with an aqueous solution of AAPC 300 g/liter,carbamide 30 g/liter and perfluoroalkylacrylate 40 g/liter, dried,heat-treated at 160° C. for 10 min. and washed. AI=29.0%, waterresistance 200 mm of water column.

The advantages of the proposed invention by comparison with the knowncompositions are confirmed by the data on the efficiency of the fireprotection effect for various fabrics given in Table 1.

TABLE 1 Composition Content of Composition of fabric, % combustionResidual for fireproofing Poly- Retarder in combustion treatment Cottonester fabric, % time, % AI, % “Proban” 100 — 12 0 31.8 80 20 10 15  27.667 33 11 Burns up 25.7 completely 50 50 12 Burns up 23.8 completely —100 11 Burns up 22.7 completely “Pyrovatex-CP” 100 — 16 0 31.7 80 20 1513  27.6 67 33 14 burns up 25.2 completely 50 50 14 burns up 23.3completely — 100 16 burns up 22.0 completely Proposed 100 0 14 0 32.5composition 80 20 15 0 32.0 67 33 16 0 31.9 50 50 15 0 30.0 — 100 13 029.1

It follows from the data in Table 1 that for the treatment of fabricscomposed of a mixture of cellulose and polyester fibres with content ofthe synthetic component more than 20%, fireproofed materials were notproduced using the compositions “Proban” and “Pyrovatex-CP” (AI<27%).Fabrics of this composition treated by the proposed process arecharacterised by quite high AI values for content of combustion retarderon the fabric of not more than 16%. There is no residual combustion timeafter the removal of the source of ignition.

What is claimed is:
 1. Process for fire protection treatment of atextile material, wherein the process includes the following sequence ofoperations: impregnation of a textile material with an aqueous solutionof melamine-formaldehyde resin; drying of the material impregnated withthis solution; impregnation of the material with an aqueous solutioncontaining carbamide and a complex compound of the ammonium salt ofamidoalkylphosphonic acid with ammonium chloride of the followingformula:

where R is an alkyl radical with 1-3 carbon atoms; drying of thematerial; and heat treatment of the material at a temperature ofapproximately 140°-170° C.
 2. Process in accordance with claim 1,wherein after the said heat treatment, the material is washed and dried.3. Process in accordance with claim 1, wherein a silicon-containingcompound is added to the aqueous solution of melamine-formaldehyderesin.
 4. Process in accordance with claim 3, wherein the said aqueoussolution contains 20-30 g/liter of melamine-formaldehyde resin and 30-50g/liter of silicon-containing compound.
 5. Process in accordance withclaim 1, wherein anion complexes of metals are added to the aqueoussolution of carbamide and the complex compound.
 6. Process in accordancewith claim 1, wherein latexes containing fluorine are introduced intothe aqueous solution of carbamide and the complex compound.
 7. Processin accordance with claim 1, wherein a textile material composed ofnatural fibres is subjected to the treatment.
 8. Process in accordancewith claim 1, wherein a textile material composed of synthetic fibres issubjected to the treatment.
 9. Process in accordance with claim 1,wherein a textile material composed of mixtures of natural and syntheticfibres is subjected to the treatment.
 10. A textile material composed ofnatural and synthetic fibres and mixtures of them, subjected tofireproofing treatment in accordance with claim
 1. 11. A process forfire protection treatment of a textile material, wherein the processincludes the following sequence of operations: impregnation of a textilematerial with an aqueous solution of silicon-containing compound; dryingof the material impregnated with this solution; impregnation of thematerial with an aqueous solution containing carbamide and a complexcompound of the ammonium salt of amidoalkylphosphonic acid with ammoniumchloride of the following formula:

where R is an alkyl radical with 1-3 carbon atoms; drying of thematerial; and heat treatment of the material at a temperature ofapproximately 140°-170° C.
 12. Process in accordance with claim 11,wherein after the said heat treatment, the material is washed and dried.13. Process in accordance with claim 11, wherein anion complexes ofmetals are added to the aqueous solution of carbamide and the complexcompound.
 14. Process in accordance with claim 11, wherein latexescontaining fluorine are added to the aqueous solution of carbamide andthe complex compound.
 15. in accordance with claim 11, wherein a textilematerial composed of synthetic fibres is subjected to the treatment. 16.Process in accordance with claim 11, wherein a textile material composedof mixtures of natural and synthetic fibres is subjected to thetreatment.
 17. A textile material composed of natural and syntheticfibres and mixtures of them subjected to fireproofing treatment inaccordance with claim
 11. 18. Composition for fire protection treatmentof a textile material wherein the composition consists of an aqueoussolution containing carbamide and a complex compound of the ammoniumsalt of amidoalkylphosphonic acid with ammonium chloride of thefollowing formula:

where R is an alkyl radical with 1-3 carbon atoms.
 19. Composition inaccordance with claim 18, wherein the composition contains (g/liter):the complex compound 200-350 carbamide 20-40 water the remainder.


20. Composition in accordance with claim 18, wherein the compositioncontains anion complexes of metals in quantity 2-10 g/liter. 21.Composition in accordance with claim 20, wherein the anion complexes ofmetals are selected from the group consisting of W, Zr and Ti. 22.Composition in accordance with claim 18, wherein the composition alsoincludes latexes containing fluorine in quantity 30-50 g/liter. 23.Composition in accordance with claim 18, wherein the compositionincludes a water repellent.
 24. Composition in accordance with claim 23,wherein the water repellent is an organosilicon substance.
 25. A textilematerial composed of natural and synthetic fibres treated with afireproofing composition in accordance with claim 18.